Drenching is the application of an aqueous solution of a chemical to control pathogens on fruit and vegetables, wherein the application is by spraying the solution onto the fruit and vegetables while such fruit and vegetables are (i) in containers positioned on a platform under, or stacked on a trailer, or the bed of a truck, parked under an intermittently operated spraying apparatus, or (ii) moved past continually operating spraying apparatus (a) in containers which are each supported and moved by a powered conveyors, (b) conveyed as separate and individual pieces by a powered roller conveyor or by a application of a conveying force, such as the introduction of additional fruit or vegetables or a powered overhead drag bar, while supported on a roller conveyor.
One major use of drenching is to control fungal infestation on fresh fruit, which commands a higher price for the grower than the same fruit does when used for juice. The percentage of any crop, such as citrus, for example, suitable for sale in the fresh market can be increased through the application of a fingicide. One typical practice for application of the fingicide to citrus fruit is to drive a truck or trailer conveying the citrus fruit into a building equipped with overhead manifolds having multiple nozzles. The truck bed or trailer, either of which is commonly referred to as a "truck", and the fruit carried in containers, either wooden boxes or plastic bins, stacked thereon, are then literally drenched with a fungicide solution discharged through the nozzles. The floor of the building is constructed to recover excess solution which drains off the truck by sloping it toward an open tank or pit set below the lowest point of the floor. The recovered solution, after addition of make-up water and fungicide concentrate to compensate for that carried off on the fruit, containers and truck, is pumped from the pit through the manifolds after the next truck is properly positioned in the building. Some of the citrus pathogens and bacteria tend to multiply in the open pit, which organisms would be distributed over the fruit along with the solution. In order to keep the populations of such organisms at acceptable levels, it has been necessary to add chlorine to the solution. Chlorine, a strong oxidizing chemical that must be carefully handled, causes the metal parts of the truck or trailer to corrode, and even tends to destroy wooden boxes by attacking the metal parts used in their construction, and when plywood is used, by attacking the adhesives adhering the plies.